If it ________ yesterday, we would have gone to the beach.
Correct: D
The correct answer is 'hadn't rained' because it is in the third conditional form, which is used for unreal or hypothetical situations in the past. However, the sentence is in the past, so we use the past perfect 'hadn't rained' to express a condition. The sentence should read: 'If it hadn't rained yesterday, we would have gone to the beach.'